Impossible Results? "The subquery didn't return all CustomerIDs for people who identify as female (F)."

Question Content:

In a car database there is a Sale table with columns, SaleID, CarID, CustomerID, LocationID, SalesRepID, SaleAmount and SaleDate and a Customer table with columns, CustomerID, FirstName, LastName, Gender and SSN.

Use a subquery as a derived table to show all sales to female ('F') customers. Select all columns from the Sale table only.